This document reports the results of the exploratory work during the PMP Heavy-Duty inter-laboratory exercise - from Oct. '07 to Feb. '08 - conducted at the Vehicles Emissions Laboratory (VELA-5) in the Transport and Air Quality Unit of the European Commission¿s Joint Research Centre (JRC, Ispra). This report presents the results of the work undertaken on an IVECO Cursor 8 Heavy-Duty engine equipped with a Continuous Regenerating Trap (CRT), i.e. the Golden Engine. Main objective of these tests were to finalize the measurement protocol that will be used in the validation exercise and the round robin. These tests included background tests, filter media effect, filter face velocity, preconditioning effect, comparisons of different particle number systems, and investigation of the golden instruments.